Heart Care

Time Widens for Giving Clot-Busting Drug for Stroke

An advisory committee of the American Stroke Association/American Heart Association has issued a recommendation that the window of time for tissue plasminogen activator (tPA) therapy be opened much wider. The advisory appears in the medical journal Stroke.

A new analysis shows that a potent clot-dissolving medication can safely be used to treat strokes four-and-a-half hours after symptoms begin.

The current recommendation allows for a three-hour deadline for the medication's use.

Researchers reviewed 1,622 cases of people treated with tPA in four separate studies and found that the benefit in keeping brain cells alive outweighs the risk of brain-damaging bleeding when the drug is given within 4.5 hours after the first symptoms of a stroke.

New Studies Confirm tPA Window

The most convincing results came from the latest study, in which 821 people were treated later than what is currently recommended.

"By pooling data from four prior clinical trials in which patients were treated with tPA between three and four-and-a-half hours, we were able to demonstrate that treatment with tPA is beneficial even if it is started between three and four-and-a-half hours of symptom onset," says study author Dr. Maarten Lansberg, at Stanford University.

"The advisory updates the current guidelines to recommend treatment in select patients in the three-to four-and-a-half hour window, but urges confirmation of the trial's results with further analyses," says the American Stroke Association/American Heart Association.

"In practical terms, wide adoption of the recommendation would mean that 2 percent to 3 percent more people who suffer strokes caused by blockage of a brain artery would receive tPA therapy," says Dr. Jeffrey L. Saver, at the University of California, Los Angeles and a member of the advisory committee.

This may not seem to be a great leap forward, but Dr. Saver noted that "right now, at well-performing hospitals, 5 percent to 10 percent of stroke patients are treated in under three hours. That disappointing number is due primarily to the widespread failure of people to know the symptoms of a stroke and take immediate action when they are seen."

"This re-emphasizes that what we need to highlight for the public is the importance of getting aid as soon as symptoms begin," notes Dr. Saver.

"Therapy with tPA is most effective when given in the first hour," he explains. "One hour is better than two, two is better than three, three is better than four."

He says that if weakness on one side of the body, trouble speaking, or trouble with vision occur, call 911 at once.

Some Patients Do Not Qualify

The chief concern with tPA is that it might cause excess bleeding that damages the brain, says Dr. Saver.

But data cited in the new study show that "for every 100 patients treated with tPA between three and four-and-a-half hours after symptoms, 16 will have a better outcome, and two or three will have a worse outcome," he says.

"The treatment has risks, but we help six patients for every one we harm," he says. "The benefit is seen in the 80 percent to 85 percent of strokes caused by an artery blockage."

Treatment with tPA is not recommended for the 10 percent to 15 percent of strokes that are caused by a burst brain vessel.

The US Food and Drug Administration (FDA) set a three-hour limit on use of tPA in strokes when it was approved 13 years ago, notes Dr. Saver. "Now we have the first expansion of guidelines for giving a clot-dissolving drug, so it is an important advance in stroke care."

But tPA should not be used beyond the three-hour limit in a number of cases, the advisory committee says - people aged 80 and older, those having a severe stroke, those with a history of stroke and diabetes, and those taking clot-preventing drugs such as Coumadin.

For anyone who has a stroke, "time lost is brain lost," says Dr. Saver. "Every minute, 2 million neurons die. What we want to see is door to needle time of 60 minutes."

Always consult your physician for more information.

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August 2009

Understanding Stroke

Stroke, also called brain attack, occurs when blood flow to the brain is disrupted.

Disruption in blood flow is caused when either a blood clot or piece of plaque blocks one of the vital blood vessels in the brain (ischemic stroke), or when a blood vessel in the brain bursts, spilling blood into surrounding tissues (hemorrhagic stroke).

The brain needs a constant supply of oxygen and nutrients in order to function.

Even a brief interruption in blood supply can cause problems. Brain cells begin to die after just a few minutes without blood or oxygen.

The area of dead cells in tissues is called an infarct.

Due to both the physical and chemical changes that occur in the brain with stroke, damage can continue to occur for several days. This is called a stroke-in-evolution.

A loss of brain function occurs with brain cell death. This may include impaired ability with movement, speech, thinking and memory, bowel and bladder, eating, emotional control, and other vital body functions.

Recovery from stroke and the specific ability affected depends on the size and location of the stroke. A small stroke may result in only minor problems such as weakness in an arm or leg.

Larger strokes may cause paralysis (inability to move part of the body), loss of speech, or even death.

According to the National Stroke Association, it is important to learn the three R's of stroke: reduce the risk, recognize the symptoms, and respond by calling 911 (or your local ambulance service).

Stroke is an emergency and should be treated as such. The greatest chance for recovery from stroke occurs when emergency treatment is started immediately.

Symptoms may be sudden and include:

weakness or numbness of the face, arm, or leg, especially on one side of the body

confusion or difficulty speaking or understanding

problems with vision such as dimness or loss of vision in one or both eyes

dizziness or problems with balance or coordination

problems with movement or walking

severe headaches with no other known cause

All of the above warning signs may not occur with each stroke. Do not ignore any of the warning signs, even if they go away - take action immediately.